1. Field of the Invention
The present invention relates to a capacitor device, and more particularly, to a capacitor device fabricated using a wafer-level process.
2. Description of the Related Art
Operating IC devices generally requires coupling capacitors to effectively reduce noise. A capacitor that is closer to the IC device will have a lower parasitic inductance and better electrical performance accordingly. Conventional capacitor types include surface mounting device type capacitors, film capacitors and trench capacitors. A conventional surface mount capacitor 1, as shown in FIG. 1, achieves high capacitance by employing multiple layers. The capacitor 1 is formed by printing an electrode 12 on a dielectric layer 10 using thick film printing techniques first and then undergoing the stacking and sintering processes, wherein the sintering temperature is generally more than 1000° C. Although the multi-layered structure results in a high capacitance, the surface mount capacitor 1 needs to be further assembled to a substrate 20, as shown in FIG. 2. Moreover, a substrate 20 is located between the decoupling capacitor 1 and the IC device 22. Besides, as there are greater demands for more compact portable electronic devices, sizes of electronic packages are minimizing, too. As such, the size of a surface mount capacitor 1 is also becoming smaller.
It is known that film capacitors are fabricated using thin-film processing techniques, and the capacitance is improved by reducing the thickness of dielectric layers. The fabrication process can integrate with IC fabrication processes, but the capacitance density per unit area is still limited. Therefore, achieving high capacitance density by utilizing multi-layer structures will increase mask numbers. Trench capacitors are fabricated by forming trenches with close, small spacing on the silicon wafer; thin layer of dielectric material is deposited in the trenches to have high capacitance density.